This fixes a bug introduced by bb51ad0, and makes the code consistent
with the logic of always allowing, while the cluster is down, commands
that don't target any key.
As a side effect the code is also simpler now.
Sometimes Redis patch releases are released in a matter of weeks or days
one after the other. In order to have less release friction the idea is
to stop writing changelogs by hand, in order to also cover everything
interesting there is to say. Useless things can be deleted manually by
the changelog. Also this gives more credits to contributors since often
in the commit message involved people are cited even when they are not
the authors of the commit.
The test works but is very slow so far, since it involves resharding
1/5 of all the cluster slots from master 0 to the other 4 masters and
back into the original master.
This fixes issue #3043.
Before this fix, after a complete resharding of a master slots
to other nodes, the master remains empty and the slaves migrate away
to other masters with non-zero nodes. However the old master now empty,
is no longer considered a target for migration, because the system has
no way to tell it had slaves in the past.
This fix leaves the algorithm used in the past untouched, but adds a
new rule. When a new or old master which is empty and without slaves,
are assigend with their first slot, if other masters in the cluster have
slaves, they are automatically considered to be targets for replicas
migration.
I've renamed maxmemoryToString to evictPolicyToString since that is
more accurate (and easier to mentally connect with the correct data), as
well as updated the function to user server.maxmemory_policy rather than
server.maxmemory. Now with a default config it is actually returning
the correct policy rather than volatile-lru.
This fix was suggested by Anthony LaTorre, that provided also a good
test case that was used to verify the fix.
The problem with the old implementation is that, the time returned by
a timer event (that is the time after it want to run again) is added
to the event *start time*. So if the event takes, in order to run, more
than the time it says it want to be scheduled again for running, an
infinite loop is triggered.
